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    Anticancer activities of manganese-based photoactivatable CO-releasing complexes (PhotoCORMs) with benzimidazole derivative ligands
    (SPRINGER, 2017) Ustun, Elvan; Ozgur, Aykut; Coskun, Kubra A.; Dusunceli, Serpil Demir; Ozdemir, Ismail; Tutar, Yusuf
    Carbon monoxide is an important signaling molecule which is produced by heme oxygenase-1. CO shows antiproliferative activity against cancer cells; hence, activation of HO-1 is a significant inhibition strategy against tumor formation and survival of cancer cells. In this work, manganese-based CO-releasing molecules (CORMs) were designed and synthesized to inhibit breast cancer cell proliferation. Human invasive ductal breast cancer cells (MCF-7) were treated with the synthesized CORMs to investigate the effect of the complexes on breast cancer survival under UV light. In vitro experiments indicated that the complexes inhibited breast cancer cell proliferation, and further, the antiproliferative effects were increased under UV light. Thus, these novel CORMs may provide a drug template for the treatment of invasive ductal breast cancer.
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    CO-releasing properties and anticancer activities of manganese complexes with imidazole/benzimidazole ligands
    (TAYLOR & FRANCIS LTD, 2016) Ustun, Elvan; Ozgur, Aykut; Coskun, Kubra A.; Demir, Serpil; Ozdemir, Ismail; Tutar, Yusuf
    Carbon monoxide (CO) is an important signaling molecule which plays significant roles in the pathogenesis of cancer. CO is produced by enzymatic degradation of heme in mammals. Heme oxygenase 1 (HO-1) catalyzes the breakdown of heme into CO, ferrous iron, and biliverdin. CO induces HO-1 and inhibits cell proliferation. Cancer cells exposed to several stress factors (hypoxia, reactive oxygen species, cis-platin, and oxidative stress), and HO-1 displays cytoprotective role against oxidative stress and inhibits apoptosis, metastases, angiogenesis, and cell proliferation processes. Therefore, metal containing CO-releasing molecules (CORMs) have been designed as an effective cancer treatment strategy. CORMs are responsible for releasing controlled amounts of CO to cells and tissues. Thus, we synthesized [Mn(CO)(3)(bpy)L]X manganese containing CORMs [bpy=2,2-bipyridine, X=hexafluorophosphate (PF6), trifluoromethanesulfonate (OTf), L=imidazole, methylimidazole, benzimidazole, N-benzylbenzimidazole, N-(4-chlorobenzyl)benzimidazole] to release CO in human invasive ductal breast (MCF-7) cell line. In vitro experiments indicated that the compounds inhibited cell proliferation and exhibited cytotoxic effect on breast cancer cells. Moreover, side groups of the compounds enhanced the anticancer effects in MCF-7 cell line. These manganese containing CORMs gave promising results and may be used as a drug template for effective treatment of invasive ductal breast carcinoma. [GRAPHICS] .
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    Designing Specific HSP70 Substrate Binding Domain Inhibitor for Perturbing Protein Folding Pathways to Inhibit Cancer Mechanism
    (Bentham Science Publ Ltd, 2021) Coskun, Kubra A.; Koca, Irfan; Gumus, Mehmet; Tutar, Yusuf
    Background: HSP70 is a survival factor for tumor cells in transformation and in tumor progression as well as in anti-apoptotic response. Objective: Several inhibitors targeting HSP70 ATPase function displayed off-target effects, but PES, which targets the HSP70 substrate binding domain, prevents tumor cell survival prominently. However, PES may not bind HSP70 in the absence of nucleotide. This research aimed to design a unique inhibitor molecule that works both in the presence and absence of nucleotides to amplify inhibition. Methods: A set of chimeric coumarine-pyrazole derivatives were determined by in silico techniques and synthesized to elucidate their inhibitory effects. Cell viability experiments displayed KBR1307 as the most efficient inhibitor. A set of characterization experiments were performed, and the results were compared to that of PES agent. Binding constant, ATP hydrolysis rate, and percent aggregation were determined in the presence and absence of inhibitors. Results: In silico docking experiments showed that only KBR1307 binds the HSP70 substrate binding domain and interacts with cochaperone interface. Binding experiments indicated that KBR1307 binds HSP70 both in the presence and absence of nucleotides, but PES does not. Both inhibitors significantly lower HSP70 ATPase activity and substrate protein disaggregation activity. However, KBR1307 displays a lower IC50 value at the MCF-7 cell line compared to PES. Both inhibitors do not alter HSP70 secondary structure composition and overall stability. Conclusion: KBR1307 effectively inhibits HSP70 compared to PES and provides a promising template for novel anticancer drug development.
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    Heat Shock Protein 40-Gok1 Isolation from Toxoplasma gondii RH Strain
    (BENTHAM SCIENCE PUBL LTD, 2013) Coskun, Kubra A.; Ozgur, Aykut; Otag, Begum; Mungan, Mesut; Tutar, Yusuf
    Toxoplasma gondii is ubiquitous obligate intracellular parasite and is one of the most important pathogen for humans and animals. In humans, T. gondii has two life forms: tachyzoites and bradyzoites. Tachyzoites form of T. gondii can cause acute infection, and it is called toxoplasmosis. The development of latent bradyzoites from rapidly growing tachyzoites has been linked to cellular and environmental stresses which are associated with heat shock proteins (Hsps). Hsps play a protective role against stressors. Hsp40 is an important member of Hsp family and T. gondii has 36 predicted Hsp40 family members. Therefore, we studied the cloning and biochemical characterization of the T. gondii RH strain Hsp40 protein-Gok1. Hsp40 prevents protein aggregation and induce refolding. Consequently, Hsp40s may play essential roles in the mechanisms of bradyzoite development and survival in the host organism. Hsp40-Gok1 functional and structural properties may facilitate drug design and protein targeting against toxoplasmosis.